The invention relates to a medical device for carrying out at least one medical function, comprising a multipart housing and at least one element that can be inserted into a body tissue of a user. The invention further relates to a protective component for use in a medical device, and to a method for protecting a functional component of a medical device. Devices and methods of this kind are used particularly in the field of medical diagnostics, preferably in the field of home monitoring, particularly for monitoring a concentration of at least one analyte in a body fluid, for example blood or interstitial fluid, for example a glucose concentration and/or cholesterol concentration. Alternatively or in addition, however, other uses are also conceivable, for example uses in the field of medication, for example for administering medicaments such as insulin, particularly in the context of insulin pumps.
From the field of medical diagnostics or therapeutics, subcutaneous devices are known, i.e. devices that are designed to be inserted wholly or partially into body tissue, for example interstitial fatty tissue. This use is also generally referred to as insertion or implantation. Examples of such subcutaneous devices can in particular be found in the field of diagnostics, for example in the field of long-term monitoring of subjects or users, particularly in the context of “home monitoring” or else in a clinical context. Accordingly, medical devices can be equipped with at least one insertable element, for example an insertable sensor for qualitative and/or quantitative detection of at least one analyte (for example at least one metabolite) in the body tissue and/or a body fluid. Sensors of this kind can be based, for example, on electrochemical and/or optical detection principles. Alternatively or in addition, the medical device can also comprise other types of insertable elements, for example medication devices that can introduce specific active ingredients into the body tissue in a targeted and preferably dosed manner, for example, insulin. Without restricting further possible fields of application, embodiments are described below mainly with reference to medical devices having insertable sensors and/or with reference to insulin pumps.
In medical therapeutics and/or diagnostics, it is often necessary to detect one or more physical and/or chemical parameters in a body tissue of a user. Examples of such physical and/or chemical parameters are analyte concentrations of one or more analytes, for example glucose and/or cholesterol. For example, depending on the parameters that are detected, a medical treatment may be chosen, for example an administration of certain medicaments, and/or a different influence on the body or body functions of the subject. In particular, the prior art has disclosed numerous examples for qualitative or quantitative detection of one or more analytes by insertable subcutaneous sensors which preferably pass through a skin surface of a user and into a body tissue, for example fatty tissue. For example, insertable sensors can be based on electrochemical measurement principles and can comprise one or more chemical substances, also referred to as test chemicals, which specifically change one or more physically and/or chemically measurable properties in the presence of the at least one analyte to be detected. Examples of such test chemicals are enzyme-based test chemicals, which can be used in electrochemical sensors for example. Other measurement principles are based, for example, on optical properties, in which at least one test chemical changes at least one optically detectable property in the presence of the at least one analyte to be detected. In the context of this disclosure, reference may be made to all of the known measurement principles.
Medical devices of this kind with insertable sensors are generally used for long-term measurement, for example for continuous or intermittent measurement over a period ranging from several days, for example seven days, to several weeks, or even one or more months. During this time, the insertable sensors remain at least partially inside the body tissue. A technical and medical challenge generally lies in inserting the insertable sensor into the body tissue, for example the subcutaneous fatty tissue, in a way that causes the least possible pain. The insertion should take place in such a way that the insertable sensor can remain at least partially in the body tissue for a relatively long period of time, for example from several hours up to several days, and can thus supply measurement data continuously or intermittently. Therefore, the prior art has disclosed a number of insertion devices which, in addition to having the insertable element, for example the sensor, also comprise one or more insertion aids. For example, insertion aids of this kind can be designed wholly or partly as insertion needles and/or cannulas, into which the insertable element can be introduced or onto which the insertable elements can be applied, in order to be implanted into the body tissue therewith. The insertion aid can subsequently be removed again, with the insertable element, for example the sensor, remaining at least partially in the body tissue. Part of the insertable element can protrude from the body tissue, for example for later removal of the insertable element and/or for connection to control electronics.
Known medical devices in the form of long-term sensors (continuous monitoring, CM) generally have at least one insertable sensor, which is placed into the subcutaneous fatty tissue, and at least one peripheral module, which is generally applied directly or indirectly to a skin surface of the user. The at least one peripheral element generally has, for example, at least one electronic amplification system for amplifying sensor signals and/or for controlling the sensor. Alternatively or in addition, further modules can be contained, for example one or more radio modules, one or more energy reservoirs and one or more protective devices. In addition to these elements, the sensor is applied using the above-described insertion devices, also referred to as inserters, which are generally used only for the purpose of insertion and are generally removed thereafter from the medical device.
Directly after the insertion of the sensor or of the insertable element, bleeding can occur at the puncture site. This bleeding generally stops by itself after a few minutes and generally has no influence on the measurement quality of the medical device. However, under some circumstances, this bleeding poses a hygiene problem if the blood that has emerged is not removed and instead remains on the wound for the period during which the medical device is applied. Moreover, plasters are generally used to hold the peripheral elements on the skin surface, and the adhesive force of these plasters can be greatly limited by the blood wetting them.
Moreover, it is known from clinical studies that external mechanical influences such as pressure and tension can affect the technical measuring performance and signal quality of inserted long-term sensors. It is also known that constant relative movement between the sensor shaft, which protrudes through the skin surface, and the wound opening leads to irritation of the wound margins and thus causes the formation of fissures. The resulting wound irritation and possible inflammation also have a negative impact on the performance and the properties of the sensor.
However, conceivable design measures for preventing relative movements between the sensor shaft and the wound opening and for reducing mechanical influences on the surrounding tissue result in design problems or present a number of design challenges. For example, a simple mechanical protection, as could be used to overcome the listed problems, would lead to a spatial problem. A mechanical protection for preventing relative movements between sensor shaft and wound opening would have to stabilize the tissue located around the wound and mechanically connect it to the sensor base, i.e. the peripheral structural element, for example the functional component, on the skin surface. For this purpose, the smallest possible spaces between sensor base and wound are advantageous. However, small spaces entail considerable hygiene problems, since blood that emerges shortly after the insertion very quickly makes contact with a closely adjacent sensor base and spreads on account of capillary forces between sensor base and skin. For reasons of space, cleaning with swabs is also made difficult by the mechanical stabilization. Moreover, reducing the mechanical influences on the tissue in which the sensor is inserted would require the stabilization and coverage of the entire tissue area. However, in order to do this, the mechanical protection would need to have a size that corresponds at least to the length of the inserted sensor. A mechanical protection of this size, however, is very inconvenient during the insertion of the sensor, since insertion aids, for example of the kind described above, have themselves a spatial extent that would collide with the dimensions of conceivable protection devices.